The present invention relates to an information storing device, and in particular to an information storing device having a plurality of working modes at recording/reproduction, which can be selected according to conditions of power supply for a device of higher rank, with which the information storing device is connected, and a method for driving same. The term xe2x80x9cinformation storing devicexe2x80x9d used here includes a rotary type information storing device such as a magnetic disk device, an optical disk device, an opto-magnetic disk device, etc. and a magnetic tape device.
The present invention can be applied to a mounted/dismounted type and a fixed type information storing devices.
Down-sizing and diversification have been attempted also for rotary type information storing devices such as a magnetic disk device, optical disk devices, opto-magnetic disk devices, etc. and magnetic tape devices, used as external storing devices, keeping step with down-sizing of electronic computers such as so-called personal computers, office computers, work stations, etc. For example, down-sizing tendency of magnetic disk devices is such that it proceeds from 3.5xe2x80x3 to 2.5xe2x80x3, to 1.8xe2x80x3 and further to 1.3xe2x80x3. Down-sizing tendency can be seen also for optical disk devices and opto-magnetic disk devices. Hereinbelow these rotary type information storing devices are generally called simply disk devices.
On the other hand, keeping step with down-sizing of the magnetic disk devices, card type mountable/dismountable magnetic disk devices according to PCMCIA (Personal Computer Memory Card International Association) standard have been developed. For example, there are known techniques disclosed in U.S. Pat. No. 5,062,016, filed May 5, 1986, JP-A-5-181565 and further JP-A-4-356785.
As a representative specification, by which standardization is intended, including interface for electric connection, there is a recommended specification on IC memory card for personal computer promoted by Corporate Juridical Person, Japanese Electronic Industry Development Association (JEIDA), in cooperation with PCMCIA in USA. Originally it was a recommended specification exclusively directed to memory card (PCMCIA Rel. 1.0/JEIDA Ver. 4.0). Thereafter it was extended to a specification (PCMCIA Rel. 2.1/JEIDA Ver. 4.2), including magnetic disk devices, keeping step with down-sizing of the magnetic disk devices.
According to this recommended specification on IC memory card for personal computer, working conditions can be set so that a relevant memory card can be used together with other cards of an electronic computer system. According to the specification the system can be so constructed that it is prohibited to use a PC card, when working conditions offered by the PC card don""t satisfy working conditions required by the system.
A parameter on power condition information is included in these working conditions. The parameter includes standard voltage of working power, minimum voltage of working power, maximum voltage of working power, current of continuous power, maximum value of mean current in 1 sec, maximum value of mean current in 10 millisec, necessary supplied current in power down mode, etc.
The system, in which use of a PC card type magnetic disk device is expected, is diversified.
That is, it extends from a work station having a sufficient power supply capacity, which demands a high speed access property from the magnetic disk device, to a portable type computer incorporating a battery, which demands low power consumption rather than access property. Therefore it is desired for the PC card type magnetic disk device used over these not specified but diversified devices of higher rank to be able to offer selectively a high speed access property or a low power consumption according to power supply capacity of a device of higher rank connected therewith.
However, as it can be seen from the recommended specification for IC memory card for personal computer published by JEIDA and PCMCIA in USA, there are no disk devices including a PC card type or a fixed type which can offer selectively a high speed access property or a low power consumption according to power supply capacity of the device of higher rank.
Personal computers of notebook size or pocket notebook size have been used more and more often outside office owing to down-sizing of computers, which has accelerated lowering of power consumption of disk devices mounted on the computers. That is, it has been tried to lower power consumption according to the tendency that smaller driving power of a disk device is more desirable. As an example thereof, there are known techniques disclosed in U.S. Pat. No. 4,933,785 (corresponding Japanese application JP-B-3-503101), in which electric power supply to circuits, for which no power is required functionally in each working mode, is suppressed by constructing a magnetic disk device so that either one of working modes can be set by classifying them into:
1) sleep mode, in which, least necessary interface function with a device of higher rank (computer system) necessary for restarting CPU being left, other circuits or function thereof are stopped;
2) idle mode, in which CPU is working and, all interface functions with the device of higher rank being left, function of a spindle motor, a servo motor, a record reproducing circuit, etc. is stopped;
3) idle mode, in which servo function is working in a state where the spindle motor is rotated and a data recording/reproducing circuit is in a stopped state; and
4) several working modes in usual operation such as a write/read mode, a seek mode, etc.
An effect to reduce mean power consumption in the different working modes can be achieved by this method. However, by this method, no attention is paid to the initial period of the spindle motor start, at which power consumption is maximum. For this reason, no effect can be obtained to reduce specifically power current at start of the disk device.
As other prior art techniques there are those disclosed in JP-A-4-205963.
By this method, the number of turns of the spindle motor is decreased to such a degree that the rotation of the disk is maintained in a waiting mode, in which write/read is not effected. This method has an effect to reduce the transient necessary maximum power current to shorten a period of time necessary for increasing the rotation of the disk to a predetermined value.
However, in a disk device in general, frequency with which the state where write/read is not effected is produced is not necessarily so high. Further, since the state where write/read is not effected is one where power consumption is smallest next to the not working state (power consumption being 0 W) where power is not switched on (power consumption is greatest at start of the motor and next greatest at file access, in either case power consumption being greater than that required when read/write is not effected while rotating the motor), as indicated in a cited reference, even if the disk motor speed is reduced by setting a waiting mode in this state where read/write is not effected, no effect to reduce remarkably power consumption can be obtained as a whole. On the contrary, considerable power is consumed temporarily, because it is required to increase the rotation speed of the disk motor upto a predetermined value, when it proceeds from this waiting mode to a write/read operation, if the read/write state is interrupted in this waiting mode.
Furthermore, since a certain period of time is required for increasing the rotation speed of the motor upto the predetermined value when it proceeds from this waiting mode to the write/read operation, this gives rise to a problem that start of the write/read operation is retarded, which lowers working speed.
In addition, in this cited reference, read/write speed is only one usual speed (one kind) and no attention is paid to setting arbitrarily diversified data read/write speeds according to needs of users.
As another prior art example, there are known techniques, by which in case where the point of time of a succeeding read/write start is previously known in a magnetic disk device, it is avoided to accelerate/decelerate the head more strongly than required to save power at seek by detecting a waiting time from seek start to read/write start and by controlling seek speed (moving speed) of the head so that the difference between this waiting time and an average seek time previously obtained for each displacement distance of the head be approximately zero, as described in JP-A-63-87663.
However no idea is disclosed to distinguish high speed seek, by which high speed processing is possible, and low speed seek effected with low noise and low power according to request of the user or according to power supply capacity of the device of higher rank. Further no attention is paid to read/write arbitrary data with different read/write speeds such as a high speed, a standard speed and a low speed according to request of the user.
As a prior art example on the high speed access property, there are known techniques, by which in order to improve operability of a reproducing device in a compact disk (CD) or a digital audio tape recorder (DAT), a second speed is automatically set for read/write of signals such as control signals TOC other than audio signals, which speed is higher than read/write speed for usual audio signals, as described e.g. in JP-A-2-156470. However, in this document, no attention is paid to record/write arbitrary data which should be used by the user with different medium speeds such as a high speed, a standard speed and a low speed or to lower power consumption according to request of the user or according to power supply capacity of the device of higher rank.
For a magnetic head used in a magnetic disk device, heretofore an inductive head is used, which produces reading voltage on the basis of the electromagnetic induction effect on winding conductor.
Recently an MR head is used, which produces reading voltage on the basis of the magneto-resistance effect. The MR head has a feature that it produces reading voltage without variations in magnetic field intensity due to relative movement of the magnetic head to a magnetic recording face. Further for the magnetic head of hard disk drive, a floating method is usually used, utilizing a hydromechanical effect acting between the head slider and the disk surface. In addition, recently a contact method called contact recording is used, by which the head slider, on which the magnetic head is mounted, is not floated.
Requirements of users for properties of a magnetic disk device or an optical disk device can be roughly classified into two types, as described below.
{circle around (1)} high speed transfer, high speed access, and
{circle around (2)} low power consumption, low noise.
In order to satisfy the requirements defined by {circle around (1)}, it is necessary to increase the read/write speed of the disk, i.e. the rotation speed and the seek speed of the head. On the contrary, in order to satisfy the requirements defined by {circle around (2)}, it is necessary to decrease the read/write speed of the disk (rotation speed) and the seek speed of the head. These two properties are contradictory to each other and there exists heretofore no disk device satisfying these two properties at the same time, but there are different models of devices, each of which has one kind of the data read/write speed and the seek speed. For this reason every user cannot help preparing at least one model of devices satisfying each of the two properties and selecting a magnetic disk device having properties suitable for utilization conditions (whether it is used under restriction on noise level and maximum power, whether the transferxc2x7access speed is regarded as important, etc.) for every use.
In this case problems as described below take place:
{circle around (1)} a magnetic disk device having either one of the properties should be selected, even if aimed utilization conditions are not clear;
{circle around (2)} there is no way other than buying another or replacement by another, when it is desired to exchange a property of a magnetic disk device with another in the course of utilization because of change in utilization conditions; and
{circle around (3)} it is impossible to switch over the properties timely according to utilization.
Particularly such problems take place for a disk device attached to a personal computer using both a commercial AC power source and an incorporated battery power source such as e.g. a notebook type personal computer. In this kind of personal computers, since sufficient power can be supplied in case where a commercial AC power source is used, it is desirable to keep the head seek speed and the disk read/write speed satisfactorily high. On the other hand, in the case where an incorporated battery power source is used, it is desirable to lower the head seek speed and the disk read/write speed to use it at a low power consumption in order to elongate continuous utilization time of the system.
However there exist no information storing devices yet, which can be used while switching working modes of access or read/write according to utilization conditions.
An object of the present invention is to provide an information storing device having a function to effect a high speed processing of the information storing device while making positively efficient use of power, when enough power is disposable and to drive the information storing device at various low power consumption modes, when disposable power is not enough, according to power conditions of the device of higher rank, with which the information storing device is connected.
Concretely speaking, it is to provide an information storing device which selects itself or has a device of higher rank select a high speed access property, a high speed processing property or a low power consumption property according to power supply capacity thereof for wide ranging devices of higher rank
1) from work stations having sufficient power supply capacities, demanding a high speed access property and a high speed processing property to the disk device
2) to battery incorporating portable type electronic computers demanding low power consumption rather than access property, etc, and performs read/write operations with the selected operation or working mode.
Another object of the present invention is to provide a disk device capable of removing the problems of the prior art techniques, by which a user can select arbitrarily one of at least two modes, which are a quick mode (high speed transferxc2x7high speed access mode) for effecting seek and data read/write and a silent mode (low speedxc2x7low power consumptionxc2x7low noise mode).
Still another object of the present invention is to provide a disk device having a switching function acting so as to select the quick mode in case where a commercial power source is used and the silent mode in case where an incorporated battery power source is used in a disk device attached to a personal computer, in which both the commercial power source and the incorporated battery power source is used.
In order to achieve the above objects an information storing device according to the present invention is constructed as follows.
The information storing device provided with means for inputting power from a device of higher rank; a device for selecting one of working modes having different necessary maximum currents; and a device for informing the device of higher device of necessary maximum current information on each of the selectable working modes.
Particularly in a device using a disk-shaped memory medium the selectable working modes are composed of combinations of:
1) different disk rotation speeds;
2) different average seek times; and
3) different times for starting the spindle motor.
In case where a magnetic tape is used, various working modes are realized by making speeds of fast forwarding and rewinding different.
Further a read head for reading out signals from data recorded in a disk may be an MR head using a magneto-resistance effect element. In addition, the contact recording method may be used, by which the magnetic head is not floated by the hydromechanical effect between the slider, on which the read head is mounted, and the surface of the magnetic disk in a region of the rotation speed of the magnetic disk in the selectable working modes.
The information storing device may comprise further a device for receiving information on current, which the device of higher rank can supply, from the device of higher rank, with which it is connected, and a device for prohibiting execution of the working modes, in which the necessary maximum current is greater than the current, which can be supplied, among the plurality of working modes.
On the other hand the device of higher rank includes a device for supplying electric power to the information storing device; a device for receiving the maximum current information of the plurality of selectable working modes having different necessary maximum currents; a device for detecting or calculating current, which the device feeding with electric power can supply, taking utilization situations into account; a device for selecting a specified working mode among the plurality of working modes; and a device for prohibiting that the working modes, in which the necessary maximum current is greater than the current, which can be supplied, are selected among the plurality of working modes.
An important effect can be obtained particularly in case where a power source (battery) is incorporated in the device of higher rank.
When a working mode, in which the necessary maximum current of the information storing device is greater than the current which can be supplied by the device feeding with electric power in the device of higher rank, is selected, either one or a plurality of following predetermined operations are effected, before electric power is supplied in reality e.g. for starting the spindle motor in the connected information storing device:
1) it is prohibited to select the specified working modes;
2) it is displayed to an operator that the specified working modes are included; and
3) a selectable working mode is executed.
By a method for controlling the device of higher rank and the information storing device, the device of higher rank is informed by the information storing device of the necessary maximum current information on each of the plurality of selectable working modes before the start of the spindle motor, which is an operation giving the greatest current, thereafter the information storing device receives a control signal for selecting one of the plurality of working modes from the device of higher rank, and the start and normal rotation of the spindle motor or operation for positioning the read head is effected according to the working mode thus selected.
By another control method, when the information storing device receives the command to start the spindle motor from the device of higher rank, while the information storing device informs the device of higher rank of the necessary maximum current information several times in a predetermined order, it stops to inform the device of higher rank of the necessary maximum current information and at last begins the start of the spindle motor in the working mode, for which the device of higher rank is informed of the necessary maximum current information.
Particularly, in an information storing device using a magnetic tape, the operation for selecting the working mode is effected before the start of the tape forwarding.
Further, in order to achieve the above objects, a disk device according to the present invention is constructed as follows.
(1) A disk device, in which a disk-shaped recording medium is rotated and at the same time a head is moved towards an aimed position on the recording medium to record data in the recording medium or to reproduce the data therefrom, comprises a head moving speed mode switching device, which switches the seek moving speed of the head by more than two steps, and a medium rotation speed mode switching device, which switches the rotation speed at recording or reproduction of the recording medium by more than two steps.
(2) A disk device according to (1) is so constructed that switching of the seek moving speed of the head and switching of the rotation speed of the recording medium are effected according to a command from the device of higher rank.
(3) A disk device according to (1) or (2) is so constructed that it has both a commercial power source and an incorporated battery power source and that the device for switching the head moving speed mode and the device for switching medium rotation speed mode switch both the seek moving speed of the head and the rotation speed of the recording medium to high speed mode, when the commercial power source is used, and both the seek moving speed of the head and the rotation speed of the recording medium to low speed mode, when the incorporated battery power source is used.
Operation based on the construction will be explained below.
According to the construction described in (1), since the seek moving speed of the head and the rotation speed of the recording medium (disk) can be switched by more than two steps, when a user wishes to effect read/write of signals at a high speed with one disk device, he can read/write in a state where the quick mode (both the head and the disk at the highest speeds) is selected, and on the contrary, when he wishes to reduce noise and power consumption, he can read/write in a state where the silent mode (both the head and the disk at the lowest speeds) is selected. Since the working mode can be selected arbitrarily, as described above, {circle around (1)} even if utilization conditions are not previously determined, it is possible to select a working mode suitable to utilization conditions determined thereafter; {circle around (2)} even if utilization conditions are changed, it is unnecessary to purchase any new disk device; and further {circle around (3)} even in the course of utilization the user can change the working mode in accordance with utilization conditions.
If a speed mode switching mechanism is so constructed that mode switching is effected by a command from the device of higher rank to a microprocessor in the disk device according to the construction described in (2) so that the user can select a suitable mode freely at any time, the user can select a desired mode simply by key operation, etc. Further, instead thereof, the switching of the mode can be effected also by means of a switch of hardware such as a jumper connector disposed on a head driving circuit and a disk motor driving circuit in the disk device.
According to the construction described in (3), in case where a commercial power source is used for power supply of a personal computer and a disk device, the quick mode of high speed read/write and high speed seek is selected so that data transfer/access of high speed and high performance can be effected. On the contrary, in case where an incorporated battery power source is used, the silent mode of low speed read/write and low speed seek is selected so that data transfer/access continuously operable for a long time can be effected with a low noise and a low power consumption.
Following advantages can be obtained by the information storing device according to the present invention.
Higher access property, higher starting property, and higher tape forwarding property can be achieved according to capacity of the power source.
Further, by using an MR head, since influences of variations in the rotation speed of the magnetic disk on the read signal are kept small, effects of the different working modes having different rotation speeds of the magnetic disk can be more efficient.
Furthermore, by using a not floated magnetic head, since influences of variations in floating amount on the read signal are kept small, effects of the different working modes having different rotation speeds of the magnetic disk can be more efficient.
Since the operator can select arbitrarily one of the selectable working modes to execute and also since the device of higher device can select suitably one working mode to execute, an effect can be obtained of efficient utilization of the incorporated power source.
An effect can be obtained that it is possible to effect driving and control of the information storing device suitable for power supply capacity of the device of higher rank. Consequently, in case where the incorporated power source is a battery, an effect can be obtained that it is possible to lengthen utilization time of the battery.
According to the present invention it is possible to use widely not only a magnetic disk device compatible with the PC card standard but also other information storing devices. That is, it is possible to provide an information storing device, a device of higher rank thereof and a method for controlling same, which can offer a high speed access property or a low power consumption property according to power supply capacity of wide ranging devices of higher rank from work stations having sufficient power supply capacity and requesting high speed access property from the information storing device to battery incorporating portable computer devices requesting low power consumption rather than access property.
Further, according to the present invention, since one disk device is so constructed that the seek speed of the head and the rotation speed of the disk recording medium can be switched by more than two steps, an effect can be obtained that the working mode can be selected arbitrarily according to request of a user, e.g. the silent mode of low speed is selected, when file access and data transfer of low noise and low power consumption are desired, while the quick mode is selected, when high speed file access and data transfer are desired. Further, since no prior art waiting mode (waiting mode, in which the rotation speed of the disk motor between different accesses to read/write is lower than the rotation speed at read/write) is adopted, an effect can be obtained that no operation for increasing (raising) the rotation speed of the motor upto a pre-determined value at successive data accesses is necessary and therefore no delay in the read/write operation due to this operation for increasing the rotation speed of the motor upto the predetermined value is produced.
Further an effect can be obtained that a user can select easily a required mode, if selection and switching of these working modes are effected by the device of higher rank.
Furthermore, in case where the present invention is applied to a personal computer, in which both a commercial power source and an incorporated battery power supply are used, such as a notebook type personal computer, an effect can be obtained that it can be used properly according to utilization conditions, because when the commercial power source is used, since the quick mode of high speed read/write and high speed seek is selected, it is possible to effect data transfer and access of high speed and high performance, and on the contrary, when the battery power source is used, since the silent mode of low speed read/write and low speed seek is selected, a long time continuous operation can be effected with low noise and low power consumption, etc.